The Seafloor Is Literally Dissolving

'Just as climate change isn't just about polar bears, ocean acidification isn't just about coral reefs.' anokato/Shutterstock

In the latest “oh my god, what are we doing to our planet” news, a recent lab-based study has shown human industrial activity is leading to ocean acidification that’s so severe it could be dissolving the seafloor in some parts of the ocean.

The ocean really is our savior. It is the world’s biggest carbon sink, absorbing colossal amounts of carbon dioxide from the Earth’s atmosphere. Without this service, the planet would have warmed 36°C (64.8°F) since the Industrial Revolution, as opposed to the 1°C (1.8°F) rise we are currently facing.

Most of this absorbed carbon dioxide remains as dissolved carbon dioxide, but a small fraction reacts with the water to form carbonic acid. Although this does increase the acidity of the water, the high amount of chalky calcite (CaCO3) in the seafloor – made up of the skeletons and shells from planktonic organisms and corals – is able to curb the severity of ocean acidification.

This new research, published in the journal Proceedings of the National Academy of Sciences, suggests that the level of carbon dioxide in the water is so high, and the water is now so acidic, that the calcite seabed is simply being dissolved. They ran simulations to pinpoint where in the world rates of calcite dissolution could be more prevalent in the coming decades.

Projections of alterations to the seabed in the future. O Sulpis et al/McGill University 

“The rate at which CO2 is currently being emitted into the atmosphere is exceptionally high in Earth’s history, faster than at any period since at least the extinction of the dinosaurs. And at a much faster rate than the natural mechanisms in the ocean can deal with, so it raises worries about the levels of ocean acidification in the future,” lead author Olivier Sulpis, who is working on his doctorate at McGill’s Department of Earth and Planetary Sciences, said in a statement.

Their findings were based on lab experiments using highly controlled, seafloor-like microenvironments because, as the researchers explain in a press release, “it is difficult and expensive to obtain measurements in the deep-sea.” So, this does mean that their study didn’t look into the real-world evidence behind the issue.

More to the point, many of these effects are yet to take effect. As Sulpis explains: “Because it takes decades or even centuries for CO2 to drop down to the bottom of the ocean, almost all the CO2 created through human activity is still at the surface. But in the future, it will invade the deep ocean, spread above the ocean floor and cause even more calcite particles at the seafloor to dissolve.”

The consequences of this are uncertain. However, it does have the potential to spark some far-reaching effects on our deep-sea oceans, as well as the fauna and flora that inhabit it. In the words of David Trossman, study author and research associate at the University of Texas-Austin: "Just as climate change isn't just about polar bears, ocean acidification isn't just about coral reefs."

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